Abstract/Summary

Records of effects of ambient ozone pollution on vegetation have been compiled for Europe for the years 1990–2006.
Sources include scientific papers, conference proceedings, reports to research funders, records of confirmed ozone
injury symptoms and an international biomonitoring experiment coordinated by the ICP Vegetation. The latter
involved ozone-sensitive (NC-S) and ozone-resistant (NC-R) biotypes of white clover (Trifolium repens L.) grown
according to a common protocol and monitored for ozone injury and biomass differences in 17 European countries,
from 1996 to 2006. Effects were separated into visible injury or growth/yield reduction. Of the 644 records of visible
injury, 39% were for crops (27 species), 38.1% were for (semi-) natural vegetation (95 species) and 22.9% were for
shrubs (49 species). Owing to inconsistencies in reporting effort from year to year it was not possible to determine
geographical or temporal trends in the data. Nevertheless, this study has shown effects in ambient air in 18 European
countries from Sweden in the north to Greece in the south. These effects data were superimposed on AOT40
(accumulated ozone concentrations over 40 ppb) and POD3gen (modelled accumulated stomatal flux over a threshold
of 3 nmolm2 s1) maps generated by the EMEP Eulerian model (50km 50km grid) that were parameterized for a
generic crop based on wheat and NC-S/NC-R white clover. Many effects were found in areas where the AOT40
(crops) was below the critical level of 3ppmh. In contrast, the majority of effects were detected in grid squares where
POD3gen (crops) were in the mid-high range (412 mmolm2). Overall, maps based on POD3gen provided better fit to
the effects data than those based on AOT40, with the POD3gen model for clover fitting the clover effects data better than that for a generic crop.